It is found that the commonly used brakes on the exercising devices are of the frictional type, the hydraulic type, the fanning type and the generator type. However, the frictional type is easily worn out and unsteady in use. As to the hydraulic type, there will be the problems of oil leaking, noise and insufficient braking torque at high temperature. Regarding the fanning type, it is too large in size and is difficult to adjust. The generator type is complicated in structure and expensive in cost.
It is, therefore, an object of the present invention to provide an adjustable magnetic brake which may obviate and mitigate the above-mentioned drawbacks.